The FTS is made of 4 separate components, (FTS web service, FTS channel agents, FTS VO agents and FTS Monitor) that can run on the same machine or on separate machines. FTS channel agents are are daemons that control a specific channel. Each network channel, e.g CERN-RAL has a distinct daemon running transfers for it. The daemon is responsible for starting and controlling transfers on the associated network link. FTS VO agents are responsible for VO-specific parts of the transfer (e.g. updating the replica catalog for a given VO or applying VO-specific retry policies in case of failed transfers). Each VO has a distinct VO agent daemon running for it. Channels and VO agents are usually know as FTA.